The win by Djokovic, the world's No. 2 player, gave Serbia an unbeatable 3-1 lead in the Davis Cup first-round matches at Belgrade Arena.
Djokovic had has hands full with the towering 6-foot-9 Isner, whom he was facing in the first reverse singles rubber. It took the Serb 4 hours, 16 minutes to dispatch the American, a 7-5, 3-6, 6-3, 6-7 (6-9), 6-4 decision on the red clay Belgrade surface.
Isner had been defeated Friday in singles play by Viktor Troicki. But he and Bob Bryan scored a U.S. win with a clutch four-set doubles victory Saturday over the Serbian duo of Janko Tipsarevic and Nenad Zimonjic, pulling the United States to within 2-1.
Copyright 2010 United Press International, Inc. (UPI).